Several different embodiments exist for arrangements that may be used for cooling electronic equipment that is housed in a rack arrangement with means for transferring heat energy that is produced in said equipment to one or more rack-related cooling units.
Cooling units with associated cooling flanges have even been arranged to provide requisite cooling, by designing and adapting the cooling unit to transfer sufficient heat energy by means of convection to the ambient air about the rack and the equipment.
It has also been shown that the heat-emitting capacity may be increased, continuously or temporarily, by using a fan unit that is designed to be able to supply the cooling unit and the cooling flanges with a stream of forced air as needed.
As examples of background art we refer to the following publications:
DE-C2-32 28 368
This publication describes an arrangement for cooling electronic equipment while using a fan unit in order to generate a forced cooling stream of air.
More specifically an arrangement is described where two incoming streams of air are permitted to pass through an upper (31) and a lower (32) opening with opposing air streams enclosed in a duct in order to pass along cooling flanges of a mutual cooling unit (33). The fan unit is positioned in the centre area of the cooling flanges.
AT-B-384 343
This publication describes that cooling flanges (5) can be encompassed by a separate wall section (13) in order to form an enclosed cooling duct. A fan unit (16) is connectable to the lower part of the cooling duct and a forced stream of air is allowed to pass along the complete cooling duct.
SE-B-85 013393-6
This publication describes an arrangement for cooling electronic equipment while using a fan unit in order to generate a forced cooling stream of air.
More specifically this publication describes an enclosure of electrical material, where the heat, generated within the enclosure (1), is conducted to the surroundings through heat exchanging between an inner and an outer air stream. At least part of the casing of the enclosure is provided with surface enlargements in order to increase the heat emission. The casing is therefore preferably given a wave-form (5) with a surface that, besides this, is provided with grooves. It is only required to supplement such enclosure with a simple cover (9) and a fan system to obtain an effective heat exchanger with a forced air stream.
U.S. Pat. No. 3,268,772
This publication describes an arrangement for cooling electronic equipment while using a fan unit in order to generate a forced cooling stream of air.
It is described that air is allowed to pass through a nozzle (87) into a cooling system (90) with a number of vents (88) in order to conduct the heat from the system. The package, including the system, is positioned on one side of the casing of the equipment.
U.S. Pat. No. 5,040,095
This publication describes an arrangement for cooling electronic equipment while using a fan unit in order to generate a forced cooling stream of air.
It is specifically shown that heat is dissipated to the ambient air through corrugated roof (35) and side panels.
DE-C2-4,209,477
This publication describes an arrangement for cooling electronic equipment while using a fan unit in order to generate a forced cooling stream of air.
The fan arrangement (21) is activated to generate an air stream along the cooling flanges (18).
As an additional example of the background art, we refer to what is shown and described in the publications EP-A1-0 564 315; EP-A2-0 449 150; U.S. Pat. No. 4,758,924; U.S. Pat. No. 5,237,486; and DE-C2-3 717 009.
A more detailed description of an application of the present invention shows that when the electronic equipment consists of a main distribution arrangement for a telephone exchange, with a so called subscriber board, the momentary heat building in the electronic equipment is directly related to, and dependent on, the momentary load, which means that heat emissions at peak hours are much greater than during normal periods of telephone traffic intensity.
It is also known that the greatest intensity at peak hour telephone traffic does not necessarily last a full hour. The actual duration may be shorter.
It is also been shown that applying a stream of forced air is an unsuitable method for cooling electronic equipment, since streams of forced air also circulate dust. Instead, cooling by means of convection is preferred.
Given the significant characteristics of the present invention, one may add that it is known that a metal's ability to absorb heat increases with volume.
It is also known that a stream of forced air that is aimed along a surface tends to follow the contours of that surface.